Hydraulic mechanism for raising and lowering flat bed trailers



June 30, 197() @HAGE 3,517,944

HYDRAULIC MECHANISM FOR RAISING AND LOWERING FLAT BED TRAILERS 0m HugoINVENTOR I, By ma June 30, 1970 o. HAGE 3,517,944

HYDRAULIC MECHANISM FOR RAISING AND LOWERING FLAT BEJD TRAILERS FiledJune s, 196e 2 sheets-sheet 2 Otto Huge INVENTOR WL.' 1K1 United StatesPatent 3,517,944 HYDRAULIC MECHANISM FOR RAISING AND LOWERING FLAT BEDTRAILERS Otto Hage, 2704 Wood Drive, Sioux Falls, S. Dak. 57105 FiledJune 3, 1968, Ser. No. 733,972 Int. Cl. B60d l 00 U.S. Cl. 280-414.5 1Claim ABSTRACT 0F THE DISCLOSURE A trailer for carrying road machineryor the like which is hinged to a dolly at one end and to the tongue atthe other end so that the trailer bed can be dropped to a position lyingon the ground. In this position the machine to be carried can be drivenonto the trailer bed, then raised into a carrying position by hydraulicmeans.

This invention pertains to trailers and more particularly to a class oftrailers used for carrying road and construction machinery and commonlyreferred to as low boy trailers.

Most trailers of this type are built with an oiset axle so that the bedof the trailer is underslung-either at about axle level or below. Inorder to load the piece of machinery onto such a trailer, it isnecessary to use planks to build a run-way up to the side of thetrailer.

By my invention, I provide a trailer in which the entire trailer bed canbe lowered onto the ground. In this position, the machine to be carriedcan be driven right up onto the platform in most cases since thethickness of the platform will cause a step of the order of four to sixinches which is negotiable by most pieces of equipment. The mechanism toaccomplish the lowering and subsequent raising of the platform iscompact and so located that there is no less space on the platform thanfor the ordinary lowboy trailer.

A more complete understanding of my invention and its embodiment may behad from a study of the following specification and the figures inwhich:

FIG. 1 is a side elevational view of my trailer in its normal travel orraised position.

FIG. 2 is a top plan view of the trailer.

FIG. 3 is an elevational view to an enlarged scale of the rear dollyshowing the trailer bed in a lowered position.

FIG. 4 is a view similar to FIG. 3 of the tongue end of the trailer.

FIG. 5 is a detailed view to an enlarged scale of the mounting 0f theholding pin for the dolly.

Briey my invention comprises a trailer having a tongue end and a wheeledend. Both ends are hinged to the bed of the trailer so that the bed canbe raised to a normal carrying position or lowered to a lower or loadingposition. Hydraulic means within the tongue at the tongue end and thedolly at the wheeled end provide the means whereby the bed can be raisedand lowered.

More specifically, and with reference to the figures, my inventionincludes a bed which provides the platform on which the machine or otherdevice is to be carried. At the forward end of the lbed I provide anupstanding bracket 11 on which the tongue is mounted.

The tongue itself is composed of a parallelogram mechanism including thefront bracket 11 to which is pivotally mounted an upper arm 12 and alower arm 13. The tongue piece 14 completes the parallelogram. In orderto provide for easy connection of the trailer to a towing vehicle, Iprefer to use a ball joint. Therefore, I have illustrated my trailer ascarrying a socket 15 xed to the 3,517,944 Patented June 30, 1970 tonguepiece 14. This is adapted to be connected to a ball on the drawbar 16 ofa truck or the like.

Between the upper arm 12 and the lower arm 13 of the parallelogrammechanism. I provide a hydraulic cylinder 18 and piston 19 assembly. Oneend of the assembly is pivotally connected to the upper arm 12 as at 20,

and the other end to the lower arm 13 or to the tongue piece 14 at alower position 21. Thus, this assembly forms a diagonal or nearly adiagonal of the parallelogram. It will now be obvious that extension ofthe assembly by forcing the piston outwardly of the cylinder will tendto move the parallelogram figure to the position shown in FIG. 1 whereasretraction of the piston will allow the parallelogram to assume theposition shown in FIG. 4.

At the end of the bed 10 opposite the tongue assembly, I provide a pairof upstanding hinge brackets 24. These brackets are a permanent part ofthe center portion or bed of the trailer and with the front bracket 11form the only obstructions on the bed. A wheeled dolly assembly 25 ispivotally connected to the brackets 24 by means of a pin 26 extendingthrough each of the brackets 24 and each of a pair of ears 27 on thedolly.

The dolly itself includes a framework on which are mounted the usualwheels 29 in a manner well known in the art. This would include theusual axles, springs etc. As best shown in FIG. 3, a hydraulic pistonand cylinder assembly 30 or a pair of assemblies is mounted between thedolly 2S and the bed 10 of the trailer. Again, the action is obvious.When the piston is forcibly retracted, the dolly is pulled toward thetrailer bed, and the bed rises because of the pivotal movement about thepins 26. When the pressure on the cylinder is relaxed, the bed islowered by the reverse action.

In order to hold thebed 10 in its upper or carrying position, I providefor a positive lock of both the dolly and the tongue in that position.In the case of the tongue, I simply provide for holes 34 (FIG. 4) in thelower arm 13 and in the bracket 11 which are aligned in the upperposition. A pin can then be inserted through the holes to hold theparallelogram mechanism in a fixed position.

In the case of the dolly, I provide a mounted pin as best shown in FIG.5. On the bed 10 of the trailer, I mount a support 32 which is generallytubular in shape. The pin 33 is slidably mounted in the support and maybe provided with a detent mechanism 35 as illustrated. The pin thereforewill extend through the opening in the ears 31 which are a part of thedolly, and thereby hold the dolly and trailer bed in the raised ortravel position. f

Withdrawal of the pin will allow the bed to be dropped, and may befacilitated at first by actuating the piston and cylinder mechanism 30to support the load while the `pin is being withdrawn.

Having thus described my invention in its embodiment, I am aware thatnumerous and extensive departures may be made therefrom withoutdeparting from the spirit and scope of the invention as limited only bythe following claim.

I claim:

1. A trailer comprising a bed, tongue means movably mounted on said bed,power operated means engaged between said tongue means and said bed,upstanding hinge brackets on said bed, dolly means hinged to said bed ata pivot line near the upper part of said brackets, second power operatedmeans connected to said dolly comprising at least one piston andcylinder assembly Within the dolly and connected to said bed at a pointsubstantially below said pivot line, ears on said dolly means extendingtoward said bed substantially below said pivot line, pin means mountedon said bed engageable with said ears to hold said bed in a raisedposition, said pin means being releasable from said ears to allowpivotal motion between said bed and said dolly whereby said bed isdropped to a lower position.

References Cited UNITED STATES PATENTS 2,653,827 9/ 1953 Manning.

2,806,710 9/ 1957 Mascaro 280-414.5

2,858,950 11/1958 Martin 214-505 4 2,922,534 1/1960 Vodraska 214-753,232,464 2/ 1966 Bogh et al. 214-512 3,346,131 10/1967 Lundell 214-512LEO FRLXGLIA, Primary Examiner U.S. C1. X.R.

